This invention relates to devices for generating axial forces in rotating shafts and, more particularly, to a device for generating an axial counterforce in a rotating shaft in response to axial displacement thereof.
In electrically powered steering arrangement in motor vehicles, for example, it is important to provide a controllable axial counterforce in response to axial displacement of a rotating shaft. Moreover, arrangements for providing such an axial counterforce to a rotating shaft are useful in many fields of engineering wherever axial counterforces must be applied in opposition to axial forces exerted on a rotating shaft, for example, to generate thresholds for open- or closed-loop control steps to be performed by the shaft.
In the context of fully electric power steering equipment for motor vehicles, an arrangement of this type is known, for instance, from FIG. 5 of German Offenlegungsschrift No. DE-OS 36 12 619. In the apparatus disclosed therein, a detent device in the form of a radially movable control pin urged toward a shaft by a preferably controllable radial force engages a circumferential shaft ring groove having flanks inclined away from the groove bottom. As a result, any axial displacement of the shaft generates an axial force that is dependent, among other factors, on the magnitude of the radial force applied by the pin and o the shape of the groove flanks. This axial force acts in a direction to counter the axial force displacing the shaft.
Because the axial distance along which the detent device can act on the shaft groove for control purposes is short, however, comparatively high radial forces must be applied by the pin.